Jerome Kaiser

Leibniz Institute for Baltic Sea Research | IOW · Marine Geology

Cyanobacterial blooms in the Baltic Sea proliferated in recent decades due to rising sea surface temperatures, resulting in significant ecological impacts. To elucidate their current success, we examined ecophysiological, biochemical, and morphological traits of recent and ~33-year-old strains of Nodularia spumigena using a resurrection approach. T...

Global warming is a major threat to marine biodiversity and ecosystem functioning, with consequences that are yet largely unknown. To frame these consequences, we need to understand how marine ecosystems respond to warming and related environmental changes. Ecosystem models have proven to be a valuable tool in this respect, but their projections va...

Marginal sea ecosystems, such as the Baltic Sea, are severely affected by anthropogenic pressures, such as climate warming, pollution, and eutrophication, which increased in the course of the past century. Biodiversity monitoring data and assessment of environmental status in such systems have typically been carried out only for the past few decade...

Sedimentary ancient DNA (sedaDNA) offers an important opportunity for investigating long‐term community dynamics. Nevertheless, sedaDNA is challenging since DNA is degraded and fragmented over time. Of particular interest for such sedaDNA studies are phytoplankton communities, which are sensitive environmental indicators and important producers in...

Multi-archive studies of climate events and archive-specific response times require synchronous time scales. Aligning common variations in the cosmogenic radionuclide production rate via curve fitting methods provides a tool for the continuous synchronization of natural environmental archives down to decadal precision. Based on this approach, we sy...

Terrestrial glacial records from the Patagonian Andes and New Zealand Alps document quasi-synchronous Southern Hemisphere–wide glacier advances during the late Quaternary. However, these records are inherently incomplete. Here, we provide a continuous marine record of western–central Patagonian ice sheet (PIS) extent over a complete glacial–intergl...

Marginal sea ecosystems, such as the Baltic Sea, are severely affected by anthropogenic pressures, such as climate warming, pollution, and eutrophication, which increased in the course of the past century. Biodiversity monitoring data and assessment of environmental status in such systems have typically been carried out only for the past few decade...

In the Mediterranean Sea, organic carbon-rich sapropels have been deposited periodically over the last fifteen million years. Some sapropels are characterized by high contents of the mat-forming, planktonic diatom Pseudosolenia calcar-avis and the planktonic diatom Thalassionema nitzschioides as a result of their mass sinking in autumn (the so-call...

Archaeal membrane lipids GDGTs (glycerol dialkyl glycerol tetraethers) are biomarkers used for tracking Earth's historical environmental changes. Among these GDGTs, the H-shaped GDGTs (H-GDGTs, or GMGTs) represent a less-explored and often overlooked subset, with its biosynthetic pathway and geological significance remaining elusive. Here, we ident...

Nitrososphaeria in the phylum Crenarchaeota, is a widespread archaeal class in the oceanic realm, playing an important role in the marine carbon and nitrogen cycle. Nitrososphaeria-derived membrane lipids, i.e., isoprenoid glycerol dialkyl glycerol tetraethers (GDGTs), are commonly employed to reconstruct past water temperatures using the TetraEthe...

As remnants of living organisms, alkenones and isoprenoid glycerol dialkyl glycerol tetraether lipids (isoGDGTs) are widely used biomarkers for determining ocean water temperatures from the past. The organisms that these proxy carriers stem from are influenced by a number of environmental parameters, such as water depth, nutrient availability, ligh...

Sedimentary DNA-based studies revealed the effects of human activity on lake cyanobacteria communities over the last centuries, yet we continue to lack information over longer timescales. Here, we apply high-resolution molecular analyses on sedimentary ancient DNA to reconstruct the history of cyanobacteria throughout the Holocene in a lake in nort...

Alkenones and Glycerol Dialkyl Glycerol Tetraether lipids (GDGT) as remnants of living organisms are widely used biomarkers for determining past oceans’ water temperatures. The organisms these proxy carriers stem from, are influenced by a number of environmental parameters, such as water depth, nutrient availability, light conditions or seasonality...

The short sediment core EMB201/7-4 retrieved from the East Gotland Basin, central Baltic Sea, is explored here as a candidate to host the stratigraphical basis for the Anthropocene series and its equivalent Anthropocene epoch, still to be formalized in the Geological Time Scale. The core has been accurately dated back to 1840 CE using a well-establ...

The Baltic Sea is a marginal sea sensitive to climate change. Relatively high sedimentation rates allow reconstructing Holocene climate variability with a high temporal resolution. The different TEX86 proxies (TEX86, TEX86L and TEX86H) based on Thaumarchaeota membrane lipids (isoprenoid glycerol dialkyl glycerol tetraethers; iGDGTs) represent a uni...

El Sistema de fiordos Baker-Martínez (Patagonia, Chile, 48ºS) es un sistema estuarino localizado entre los Campos de Hielo Norte y Sur, conectando la Cordillera de los Andes al este con el Océano Pacífico al oeste. Recibe agua dulce y aportes de sedimentos de cuatro ríos alimentados por glaciares, y del Glaciar Jorge Montt. Se utilizó un testigo de...

Since the beginning of the Anthropocene, lacustrine biodiversity has been influenced by climate change and human activities. These factors advance the spread of harmful cyanobacteria in lakes around the world, which affects water quality and impairs the aquatic food chain. In this study, we assessed changes in cyanobacterial community dynamics via...

The stress on the environment is increasing as the human population living on it increases. Water eutrophication, a leading cause of impairment of many freshwater and coastal marine ecosystems in the world, is a typical consequence of anthropogenic pressure on the environment. The Baltic Sea represents an excellent example of eutrophication-related...

Understanding hemisphere‐wide millennial‐scale temperature variability during past glacials in response to ice sheet dynamics and orbital forcing is one of the key targets for Quaternary climate research. While an inland propagation of abrupt temperature changes into Eurasia from the North Atlantic realm during the last glacial (Weichselian) receiv...

Summer cyanobacterial blooms represent a threat to the Baltic Sea ecosystem, causing deoxygenation of the bottom water and the spread of the so-called dead zones. The history of the Baltic Sea cyanobacterial blooms is known from in situ and satellite observations since the early 1980s but is still not well understood. By comparing both weekly resol...

Modern hydrated Mg rich stromatolites are actively growing along the shallow shorelines of Lake Salda (SW Turkey). An integrated approach involving isotopic, mineralogical, microscopic, and organic/geochemical techniques along with culture-independent molecular methods were applied to various lake samples to assess the role of microbial processes o...

Abstract. Summer cyanobacterial blooms represent a threat for the Baltic Sea ecosystem, causing deoxygenation of the bottom water and the spread of the so-called dead zones. The time history of the Baltic Sea cyanobacterial blooms is known from in situ and satellite observations since the early 1980s, but still not well understood. By comparing bot...

During the construction of an expressway in NW Poland in 2016, sediments of a fossil lake were revealed. This sedimentary complex reaching a thickness of 11 m is encompassed by fluvial sand. The lake had a maximum water depth of 20 m and covered at least 12 km2. In one of the sedimentary facies, an almost complete skeleton of the rhinoceros Stephan...

Detailed temperature reconstructions over the past 2,000 years are important for contextualizing modern climate change. The midlatitude SE Pacific is a key region in this regard in terms of understanding the climatic linkages between the tropics and southern high latitudes. Multicentennial timescale temperature variability remains, however, poorly...

Isochrysidales species of the phylum Haptophyta are the exclusive producers of C37 to C42 long chain alkyl ketones, also called long chain alkenones (LCAs). While LCA distributions are known to vary with temperature and salinity, it is difficult to tease apart the direct effects of environmental parameters vs changes in the LCA-producing organisms....

The Black Sea repeatedly experienced major hydrographic changes during glacial-interglacial transitions, with alternating limnic and brackish stages. While the redox conditions during the present Holocene brackish period (since ∼. 9,000. yr. BP) have been intensively studied, the redox evolution during the last interglacial, the Eemian (∼. 128,000-...

The anthropogenically forced expansion of coastal hypoxia is a major environmental problem affecting coastal ecosystems and biogeochemical cycles throughout the world. The Baltic Sea is a semi-enclosed shelf sea whose central deep basins have been highly prone to deoxygenation during its Holocene history, as shown previously by numerous paleoenviro...

Sedimentary time markers based on the recent history of anthropogenic radionuclides or pollutants are extremely valuable in synchronizing and calibrating proxy-based records with instrumental data and observations. However, such time markers are rare for the early 20th century, and any additional time marker for this time period would be valuable f...

The anthropogenically forced expansion of coastal hypoxia is a major environmental problem affecting coastal ecosystems and biogeochemical cycles throughout the world. The Baltic Sea is a semi-enclosed shelf sea whose central deep basins have been highly prone to deoxygenation during its Holocene history, as shown previously by numerous paleoenviro...

C37 alkenones produced by certain haptophytes of the Isochrysidales are valuable sedimentary biomarkers used to estimate sea surface temperature (SST) in the open ocean. However, in coastal seas the role of salinity gradients on alkenone producing species and SST estimates is poorly known. Alkenones were analysed in surface sediments from the marin...

The Paleoclimate Model Intercomparison Project (PMIP) aims to simulate the response of Earth's climate system to changes in different climate forcing factors, focusing on six key intervals of the geological past (the mid-Piacenzian Warm Period at ∼3.3-3.0 Ma, the last interglacial period at ∼ 127 ka, the last glacial maximum at ∼21 ka, the mid-Holo...

Lake Salda located in south-western Anatolia is characterized by the presence of living stromatolites and by a low diversity of both phytoplankton and zooplankton due to high pH and magnesium concentration. The most abundant, free sedimentary lipids of the uppermost centimetres of the lake sediments were studied as potential environmental biomarker...

The Marine Isotope Stage (MIS) 3 stands out due to its abrupt changes from cold and dry stadials to warm and humid interstadials, the so-called Dansgaard-Oeschger cycles that also affected temperature and rainfall in the Black Sea region. This study is based on a gravity core from the southeastern (SE) Black Sea that covers the last glacial lake st...

The Baltic Sea is a shallow, semi-enclosed and intra-continental shelf sea characterized by anoxic bottom waters in the deepest basins, allowing for the preservation of sedimentary organic matter. In the present study, the most abundant, naturally-occurring lipids in surface sediments from the entire Baltic Sea and the Skagerrak area were identifie...

C25 and C30 highly branched isoprenoid (HBI) alkenes are lipid biomarkers produced exclusively by certain diatoms and found in sediments worldwide. Here, for the first time, it is shown that the marine planktonic diatom Pseudosolenia calcar-avis (Schultze) (Sundström, B.G., 1986. The Marine Diatom Genus Rhizosolenia (A New Approach to the Taxonomy)...

The Eurasian inland propagation of temperature anomalies during glacial millennial-scale climate variability is poorly understood but this knowledge is crucial to understanding hemisphere-wide atmospheric teleconnection patterns and climate mechanisms. Based on biomarkers and geochemical paleothermometers, a pronounced continental temperature varia...

Proxies based on glycerol dialkyl glycerol tetraether (GDGT) lipids from archaea [isoprenoid GDGTs] and bacteria [branched (br) GDGTs] in 33 surface sediments from marine, fjord and lake systems between 25°S and 50°S in Chile were analyzed. The regional TEXH86 calibration obtained from the marine and fjord sediments and mean annual surface temperat...

Significance The Drake Passage (DP) represents the most important oceanic gateway along the pathway of the world’s largest current: the Antarctic Circumpolar Current (ACC). Resolving changes in the flow of circumpolar water masses through the DP is crucial for advancing our understanding of the Southern Ocean’s role in affecting ocean and climate c...

The Eurasian inland propagation of temperature anomalies during glacial millennial-scale climate variability is poorly understood but this knowledge is crucial to understanding hemisphere-wide atmospheric teleconnection patterns and climate mechanisms. Based on biomarkers and geochemical paleothermometers, a pronounced continental temperature varia...

The Drake Passage (DP) is the major geographic constriction for the Antarctic Circumpolar Current (ACC) and exerts a strong control on the exchange of physical, chemical, and biological properties between the Atlantic, Pacific, and Indian Ocean basins. Resolving changes in the flow of circumpolar water masses through this gateway is, therefore, cru...

This project aimed at investigating centennial to millennial-scale changes of the strength and position of the southern westerly wind belt (SWW) using multi-proxy paleoprecipitation and paleoceanographic records combined with transient model runs. The proxy data records reveal a distinct latitudinal anti-phasing of wind changes between the core and...

Here we provide three new Holocene (11–0 cal ka BP) alkenone-derived sea surface temperature (SST) records from the southernmost Chilean fjord region (50–53°S). SST estimates may be biased towards summer temperature in this region, as revealed by a large set of surface sediments. The Holocene records show consistently warmer than present-day SSTs e...

A series of molecular organic markers were determined in surface sediments from the Gulf of Genoa (Ligurian Sea) in order to evaluate their potential for palaeo-environmental reconstructions. Allochthonous input can be characterized by the distributions of n-C29 and n-C31 alkanes, n-C26 and n-C28 alkanols and branched glycerol dialkyl glycerol tetr...

A series of molecular organic markers were determined in surface sediments from the Gulf of Genoa (Ligurian Sea) in order to evaluate their potential for palaeo-environmental reconstructions. Allochthonous input can be characterized by the distributions of n-C29 and n-C31 alkanes, n-C26 and n-C28 alkanols and branched glycerol dialkyl glycerol tetr...

The last glacial-interglacial transition or Termination I (T I) is well documented in the Black Sea, whereas little is known about climate and environmental dynamics during the penultimate Termination (T II). Here we present a multi-proxy study based on a sediment core from the SE Black Sea covering the penultimate glacial and almost the entire Eem...

The epicontinental Black Sea is very sensitive to environmental changes thus forming an ideal archive of regional climate change and teleconnective responses to the coupled North Atlantic ocean-atmosphere system. Here we focus on the climatic and hydrological evolution of the SE Black Sea during the glacial-interglacial transition of Termination II...

Glacial millennial-scale paleoceanographic changes in the Southeast Pacific and the adjacent Southern Ocean are poorly known due to the scarcity of well-dated and high resolution sediment records. Here we present new surface water records from sediment core MD07-3128 recovered at 53°S off the Pacific entrance of the Strait of Magellan. The alkenone...

Glacial millennial-scale paleoceanographic changes in the Southeast Pacific and the adjacent Southern Ocean are poorly known due to the scarcity of well-dated and high resolution sediment records. Here we present new surface water records from sediment core MD07-3128 recovered at 53°S off the Pacific entrance of the Strait of Magellan. The alkenone...

The position and intensity of the southern westerly wind belt varies seasonally as a consequence of changes in sea surface temperature. During the austral winter, the belt expands northward and the wind intensity in the core decreases. Conversely, during the summer, the belt contracts, and the intensity within the core is strengthened. Reconstructi...

Antarctic and Greenland ice-core records reveal large fluctuations of dust input on both orbital and millennial time-scales with potential global climate implications. At least during glacial periods, the Antarctic dust fluctuations appear to be largely controlled by environmental changes in southern South America. We compare dust flux records from...

The position and intensity of the southern westerly wind belt varies seasonally as a consequence of changes in sea surface temperature. During the austral winter, the belt expands northward and the wind intensity in the core decreases. Conversely, during the summer, the belt contracts, and the intensity within the core is strengthened. Reconstructi...

Antarctic and Greenland ice-core records reveal large fluctuations of dust input on both orbital and millennial time-scales with potential global climate implications. At least during glacial periods, the Antarctic dust fluctuations appear to be largely controlled by environmental changes in southern South America. We compare dust flux records from...

ODP Site /GeoB 3313 located at the upper continental slope off southern Chile (41°S) is ideally located to study latitudinal shifts of atmospheric and oceanographic circulation off southwestern South America. Extraordinarily high sedimentation-rates allow for high resolution reconstructions and detailed comparisons of various continental climate an...

Current knowledge suggests that the fractionation of hydrogen isotopes in plants is relatively constant, such that the dD values of leaf waxes derived from terrestrial plants, which obtain their hydrogen from meteoric water, have the potential to record changes in the isotopic composition of the hydrogen source. However, studies have shown that oth...

We present paleoceanographic and continental paleoclimate data from sediment core MD07-3128 recovered during IMAGES XV-MD159-PACHIDERME cruise off southernmost Chile. The coring site is located at ~53°S at the continental slope (~1000 m water depth) off the Pacific entrance of the Strait of Magellan. Based on the preliminary stratigraphy (14C and p...

Postglacial changes in the latitudinal pattern and intensity of the Southern Hemispheric Westerly Wind Belt (SHW) are still poorly constrained and discussed controversially. Here we address the postglacial SHW evolution based on new and also published data from the southwest coast of South America between 33 and 54°S. Three marine and one lacustrin...

Southernmost South America is best located to study past changes in the location/strength/extension of the SWW as it is the only land within the SWW pathway. We present here new results based on archives from marine, fjord and terrestrial environments located in the Chilean mid- to high latitudes aiming to frame the SWW variability at millennial to...

The synchronization of ice cores from Antarctica and Greenland using methane concentrations provides strong evidence for thermal seesaw pattern in the Northern and Southern Hemisphere during abrupt climate changes in the last glacial period and the last deglaciation. Modeling studies show that changes in temperature, sea ice extent and/or salinity...

The Holocene climate variability in south-central Chile is most notably regulated by changes in the latitudinal position and in the intensity of the Southern Westerly Winds (SWW). While a more southward position of the SWW during the early Holocene implied dry and warm conditions, a northward shift of the wind belt led to a general cooling trend an...

North central Chile is located at an important climatic transition zone between humid conditions under the influence of the Southern Hemisphere Westerly Winds in the south and the extremely dry climate of the Atacama Desert in the north. Offshore, equatorward flowing cold waters of the Peru–Chile Current converge with relatively warmer waters comin...

The termination of the last ice age (Termination 1; T1) is crucial for our understanding of global climate change and for the validation of climate models. There are still a number of open questions regarding for example the exact timing and the mechanisms involved in the initiation of deglaciation and the subsequent interhemispheric pattern of the...

A high-resolution multiproxy study performed on a marine record from SE Pacific off southern South America was used to reconstruct past regional environmental changes and their relation to global climate, particularly to El Niño/Southern Oscillation (ENSO) phenomenon during the last 2200 years. Our results suggest a sustained northward shift in the...

The ultra-high sedimentation rates at ODP Site 1233, situated at 41°S off Chile, enabled the investigation of the millennial to multi-centennial scale relationship and variability of the Patagonian Ice Sheet (PIS) extent, as indicated by the Fe relative concentration record, and offshore sea surface temperatures (SST) during the last glacial period...

This chapter examines ancient and modern geological and oceanographic processes relevant to that part of the Pacific Ocean lying offshore from the Chilean mainland. Initial overviews are presented of submarine geomorphology, plate tectonic background, Chilean physiography, oceanic circulation and present-day climate. These are followed by an examin...

The termination of the last ice age (Termination 1; T1) is crucial for our understanding of global climate change and for the validation of climate models. There are still a number of open questions regarding for example the exact timing and the mechanisms involved in the initiation of deglaciation and the subsequent interhemispheric pattern of the...

A high-resolution multiproxy study performed on a marine record from SE Pacific off southern South America was used to reconstruct past regional environmental changes and their relation to global climate, particularly to El Niño/Southern Oscillation (ENSO) phenomenon during the last 2200 years. Our results suggest a sustained northward shift in the...

Many variables have been used to reconstruct Chilean paleoenvironmental changes during the late Quaternary. In this paper we present an overview of a number of these variables, so-called proxies, that have been inferred from marine sediments from the Chilean continental margin and summarise the results. In general, a glacial-interglacial pattern of...

1] We report the last glacial-interglacial transition of marine denitrification off northern Chile based on sedimentary nitrogen isotopes. Our results show a relatively early, large and abrupt transition from low to high denitrification regimes consistent with recently-reported data from off Peru. The deglaciation is characterized by millennial-sca...